/Engine/Plugins/Developer/Concert/ConcertSync/ConcertSyncClient/Source/ConcertSyncClient/Public/IConcertSyncClient.h
Get the delegate called just before the workspace gets created.
[FOnConcertClientSyncSessionStartupOrShutdown](API\Plugins\ConcertSyncClient\FOnConcertClientSyncSessionStart-) & OnSyncSessionStartup()